The purpose of this investigation was to examine the effects of continuous (CBFR) and intermittent (IBFR) blood flow restriction (BFR) applied during sprint interval training (SIT) on performance, muscle, and neuromuscular function. Fifteen men completed SIT with CBFR, IBFR, and No-BFR. Each SIT bout consisted of 2, 30-s maximal sprints on a cycle ergometer with a resistance of 7.5% of body mass. Concentric peak torque (CPT), maximal voluntary isometric contraction (MVIC) torque, and muscle thickness (MT) were measured before and after the SIT protocols during each visit. During the maximal strength assessments, surface electromyography (sEMG) was recorded and during each SIT, peak and mean RPM were measured, and power output was examined relative to the sEMG-based physical working capacity at the fatigue threshold (PWCFT). CPT and MVIC torque decreased from pretest (220.3±47.6 Nm and 355.1±72.5 Nm) to posttest (147.9±27.7 Nm and 252.2±45.5 Nm), while MT increased (1.77±0.31 cm to 1.96±0.30 cm). There were no changes in sEMG amplitude assessed during the CPT (+6.5±22.5%) and MVIC (+7.7±24.1%) muscle actions, while sEMG mean power frequency decreased during the CPT (-12.8±10.5%) and MVIC (-8.7±10.2%) muscle actions. Collapsed across Sprint, %PWCFT was greater during No-BFR (414.2±121.9%) than CBFR (375.9±121.9%). Peak and mean RPM decreased from Sprint 1 to Sprint 2 for No-BFR (157.7±12.5 and 110.4±7.1 RPM to 147.5±12.8 and 85.5±9.9 RPM), CBFR (153.9±14.5 and 105.2±11.5 RPM to 129.2±13.5 and 73.6±14.0 RPM) and IBFR (158.0±14.4 and 110.3±8.6 RPM to 134.1±15.7 and 81.2±12.5 RPM). During Sprint 1, mean RPM was greater for No-BFR than CBFR, while during Sprint 2, both No-BFR and IBFR were greater than CBFR. Collectively, the findings of the present study indicated that SIT with or without BFR did not affect neuromuscular function and induced comparable reductions in neuromuscular fatigue and sprint performance across all conditions
